#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;


 // Definition for a binary tree node.
    struct TreeNode {
       int val;
      TreeNode *left;
      TreeNode *right;
      TreeNode(int x) : val(x), left(NULL), right(NULL) {}
  };
 
class Solution {
public:
    TreeNode* buildTree(vector<int>& preorder, vector<int>& inorder) {
        
    }
};